acpi: Support writing a name

ACPI supports storing names which are made up of multiple path components.
Several special cases are supported. Add a function to emit a name.

Signed-off-by: Simon Glass <sjg@chromium.org>
Reviewed-by: Wolfgang Wallner <wolfgang.wallner@br-automation.com>
Reviewed-by: Bin Meng <bmeng.cn@gmail.com>

4 files changed, 231 insertions, 0 deletions

diff --git a/include/acpi/acpigen.h b/include/acpi/acpigen.h
index 14b96203a9..24aec7fad6 100644
--- a/include/acpi/acpigen.h
+++ b/include/acpi/acpigen.h
@@ -21,12 +21,15 @@ struct acpi_ctx;
 enum {
 	ZERO_OP			= 0x00,
 	ONE_OP			= 0x01,
+	NAME_OP			= 0x08,
 	BYTE_PREFIX		= 0x0a,
 	WORD_PREFIX		= 0x0b,
 	DWORD_PREFIX		= 0x0c,
 	STRING_PREFIX		= 0x0d,
 	QWORD_PREFIX		= 0x0e,
 	PACKAGE_OP		= 0x12,
+	DUAL_NAME_PREFIX	= 0x2e,
+	MULTI_NAME_PREFIX	= 0x2f,
 };
 
 /**
@@ -165,4 +168,26 @@ void acpigen_write_integer(struct acpi_ctx *ctx, u64 data);
  * @str: String to write
  */
 void acpigen_write_string(struct acpi_ctx *ctx, const char *str);
+
+/**
+ * acpigen_emit_namestring() - Emit an ACPI name
+ *
+ * This writes out an ACPI name or path in the required special format. It does
+ * not add the NAME_OP prefix.
+ *
+ * @ctx: ACPI context pointer
+ * @namepath: Name / path to emit
+ */
+void acpigen_emit_namestring(struct acpi_ctx *ctx, const char *namepath);
+
+/**
+ * acpigen_write_name() - Write out an ACPI name
+ *
+ * This writes out an ACPI name or path in the required special format with a
+ * NAME_OP prefix.
+ *
+ * @ctx: ACPI context pointer
+ * @namepath: Name / path to emit
+ */
+void acpigen_write_name(struct acpi_ctx *ctx, const char *namepath);
 #endif
diff --git a/include/test/ut.h b/include/test/ut.h
index 7ddd6e8872..99bbb1230c 100644
--- a/include/test/ut.h
+++ b/include/test/ut.h
@@ -134,6 +134,23 @@ int ut_check_console_dump(struct unit_test_state *uts, int total_bytes);
 	}								\
 }
 
+/*
+ * Assert that two string expressions are equal, up to length of the
+ * first
+ */
+#define ut_asserteq_strn(expr1, expr2) {				\
+	const char *_val1 = (expr1), *_val2 = (expr2);			\
+	int _len = strlen(_val1);					\
+									\
+	if (memcmp(_val1, _val2, _len)) {				\
+		ut_failf(uts, __FILE__, __LINE__, __func__,		\
+			 #expr1 " = " #expr2,				\
+			 "Expected \"%.*s\", got \"%.*s\"",		\
+			 _len, _val1, _len, _val2);			\
+		return CMD_RET_FAILURE;					\
+	}								\
+}
+
 /* Assert that two memory areas are equal */
 #define ut_asserteq_mem(expr1, expr2, len) {				\
 	const u8 *_val1 = (u8 *)(expr1), *_val2 = (u8 *)(expr2);	\
diff --git a/lib/acpi/acpigen.c b/lib/acpi/acpigen.c
index b254ef6c9a..0a6c1e37c5 100644
--- a/lib/acpi/acpigen.c
+++ b/lib/acpi/acpigen.c
@@ -153,3 +153,99 @@ void acpigen_write_string(struct acpi_ctx *ctx, const char *str)
 	acpigen_emit_byte(ctx, STRING_PREFIX);
 	acpigen_emit_string(ctx, str);
 }
+
+/*
+ * The naming conventions for ACPI namespace names are a bit tricky as
+ * each element has to be 4 chars wide ("All names are a fixed 32 bits.")
+ * and "By convention, when an ASL compiler pads a name shorter than 4
+ * characters, it is done so with trailing underscores ('_')".
+ *
+ * Check sections 5.3, 20.2.2 and 20.4 of ACPI spec 6.3 for details.
+ */
+static void acpigen_emit_simple_namestring(struct acpi_ctx *ctx,
+					   const char *name)
+{
+	const char *ptr;
+	int i;
+
+	for (i = 0, ptr = name; i < 4; i++) {
+		if (!*ptr || *ptr == '.')
+			acpigen_emit_byte(ctx, '_');
+		else
+			acpigen_emit_byte(ctx, *ptr++);
+	}
+}
+
+static void acpigen_emit_double_namestring(struct acpi_ctx *ctx,
+					   const char *name, int dotpos)
+{
+	acpigen_emit_byte(ctx, DUAL_NAME_PREFIX);
+	acpigen_emit_simple_namestring(ctx, name);
+	acpigen_emit_simple_namestring(ctx, &name[dotpos + 1]);
+}
+
+static void acpigen_emit_multi_namestring(struct acpi_ctx *ctx,
+					  const char *name)
+{
+	unsigned char *pathlen;
+	int count = 0;
+
+	acpigen_emit_byte(ctx, MULTI_NAME_PREFIX);
+	pathlen = ctx->current;
+	acpigen_emit_byte(ctx, 0);
+
+	while (*name) {
+		acpigen_emit_simple_namestring(ctx, name);
+		/* find end or next entity */
+		while (*name != '.' && *name)
+			name++;
+		/* forward to next */
+		if (*name == '.')
+			name++;
+		count++;
+	}
+
+	*pathlen = count;
+}
+
+void acpigen_emit_namestring(struct acpi_ctx *ctx, const char *namepath)
+{
+	int dotcount;
+	int dotpos;
+	int i;
+
+	/* We can start with a '\' */
+	if (*namepath == '\\') {
+		acpigen_emit_byte(ctx, '\\');
+		namepath++;
+	}
+
+	/* And there can be any number of '^' */
+	while (*namepath == '^') {
+		acpigen_emit_byte(ctx, '^');
+		namepath++;
+	}
+
+	for (i = 0, dotcount = 0; namepath[i]; i++) {
+		if (namepath[i] == '.') {
+			dotcount++;
+			dotpos = i;
+		}
+	}
+
+	/* If we have only \\ or only ^* then we need to add a null name */
+	if (!*namepath)
+		acpigen_emit_byte(ctx, ZERO_OP);
+	else if (dotcount == 0)
+		acpigen_emit_simple_namestring(ctx, namepath);
+	else if (dotcount == 1)
+		acpigen_emit_double_namestring(ctx, namepath, dotpos);
+	else
+		acpigen_emit_multi_namestring(ctx, namepath);
+}
+
+void acpigen_write_name(struct acpi_ctx *ctx, const char *namepath)
+{
+	acpigen_emit_byte(ctx, NAME_OP);
+	acpigen_emit_namestring(ctx, namepath);
+}
diff --git a/test/dm/acpigen.c b/test/dm/acpigen.c
index c360f55dd3..adfcf88765 100644
--- a/test/dm/acpigen.c
+++ b/test/dm/acpigen.c
@@ -505,3 +505,96 @@ static int dm_test_acpi_string(struct unit_test_state *uts)
 	return 0;
 }
 DM_TEST(dm_test_acpi_string, 0);
+
+/* Test writing a name */
+static int dm_test_acpi_name(struct unit_test_state *uts)
+{
+	struct acpi_ctx *ctx;
+	u8 *ptr;
+
+	ut_assertok(alloc_context(&ctx));
+
+	ptr = acpigen_get_current(ctx);
+
+	/*
+	 * The names here are made up for testing the various cases. The
+	 * grammar is in the ACPI spec 6.3 section 19.2.2
+	 */
+	acpigen_write_name(ctx, "\\_SB");
+	acpigen_write_name(ctx, "\\_SB.I2C0");
+	acpigen_write_name(ctx, "\\_SB.I2C0.TPM2");
+	acpigen_write_name(ctx, "\\_SB.I2C0.TPM2.LONG");
+	acpigen_write_name(ctx, "^^^^SPI0.FLAS");
+	acpigen_write_name(ctx, "NN");
+	acpigen_write_name(ctx, "^AB.CD.D.EFG");
+	acpigen_write_name(ctx, "^^^^");
+	acpigen_write_name(ctx, "\\");
+	acpigen_write_name(ctx, "\\ABCD");
+
+	ut_asserteq(107, acpigen_get_current(ctx) - ptr);
+	ut_asserteq(NAME_OP, ptr[0]);
+	ut_asserteq_strn("\\_SB_", (char *)ptr + 1);
+	ptr += 6;
+
+	ut_asserteq(NAME_OP, ptr[0]);
+	ut_asserteq('\\', ptr[1]);
+	ut_asserteq(DUAL_NAME_PREFIX, ptr[2]);
+	ut_asserteq_strn("_SB_I2C0", (char *)ptr + 3);
+	ptr += 11;
+
+	ut_asserteq(NAME_OP, ptr[0]);
+	ut_asserteq('\\', ptr[1]);
+	ut_asserteq(MULTI_NAME_PREFIX, ptr[2]);
+	ut_asserteq(3, ptr[3]);
+	ut_asserteq_strn("_SB_I2C0TPM2", (char *)ptr + 4);
+	ptr += 16;
+
+	ut_asserteq(NAME_OP, ptr[0]);
+	ut_asserteq('\\', ptr[1]);
+	ut_asserteq(MULTI_NAME_PREFIX, ptr[2]);
+	ut_asserteq(4, ptr[3]);
+	ut_asserteq_strn("_SB_I2C0TPM2LONG", (char *)ptr + 4);
+	ptr += 20;
+
+	ut_asserteq(NAME_OP, ptr[0]);
+	ut_asserteq('^', ptr[1]);
+	ut_asserteq('^', ptr[2]);
+	ut_asserteq('^', ptr[3]);
+	ut_asserteq('^', ptr[4]);
+	ut_asserteq(DUAL_NAME_PREFIX, ptr[5]);
+	ut_asserteq_strn("SPI0FLAS", (char *)ptr + 6);
+	ptr += 14;
+
+	ut_asserteq(NAME_OP, ptr[0]);
+	ut_asserteq_strn("NN__", (char *)ptr + 1);
+	ptr += 5;
+
+	ut_asserteq(NAME_OP, ptr[0]);
+	ut_asserteq('^', ptr[1]);
+	ut_asserteq(MULTI_NAME_PREFIX, ptr[2]);
+	ut_asserteq(4, ptr[3]);
+	ut_asserteq_strn("AB__CD__D___EFG_", (char *)ptr + 4);
+	ptr += 20;
+
+	ut_asserteq(NAME_OP, ptr[0]);
+	ut_asserteq('^', ptr[1]);
+	ut_asserteq('^', ptr[2]);
+	ut_asserteq('^', ptr[3]);
+	ut_asserteq('^', ptr[4]);
+	ut_asserteq(ZERO_OP, ptr[5]);
+	ptr += 6;
+
+	ut_asserteq(NAME_OP, ptr[0]);
+	ut_asserteq('\\', ptr[1]);
+	ut_asserteq(ZERO_OP, ptr[2]);
+	ptr += 3;
+
+	ut_asserteq(NAME_OP, ptr[0]);
+	ut_asserteq_strn("\\ABCD", (char *)ptr + 1);
+	ptr += 5;
+
+	free_context(&ctx);
+
+	return 0;
+}
+DM_TEST(dm_test_acpi_name, 0);